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authorMatthew Wilcox <willy@linux.intel.com>2016-05-20 17:01:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-20 17:58:30 -0700
commitdb050f2924fcf39428bdadf28970a32cfaf256ef (patch)
treec9b09f6a0593ba85a4838913e21be9b5dc8b584d /lib
parent57578c2ea2cb2e0d362a9212ac83cf90221d4883 (diff)
downloadlinux-db050f2924fcf39428bdadf28970a32cfaf256ef.tar.gz
radix-tree: add missing sibling entry functionality
The code I previously added to enable multiorder radix tree entries was untested and therefore buggy. This commit adds the support functions that Ross and I decided were necessary over a four-week period of iterating various designs. Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Jan Kara <jack@suse.com> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/radix-tree.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 799f341977d0..585965afc808 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -80,6 +80,46 @@ static inline void *indirect_to_ptr(void *ptr)
return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
}
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+/* Sibling slots point directly to another slot in the same node */
+static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
+{
+ void **ptr = node;
+ return (parent->slots <= ptr) &&
+ (ptr < parent->slots + RADIX_TREE_MAP_SIZE);
+}
+#else
+static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node)
+{
+ return false;
+}
+#endif
+
+static inline unsigned long get_slot_offset(struct radix_tree_node *parent,
+ void **slot)
+{
+ return slot - parent->slots;
+}
+
+static unsigned radix_tree_descend(struct radix_tree_node *parent,
+ struct radix_tree_node **nodep, unsigned offset)
+{
+ void **entry = rcu_dereference_raw(parent->slots[offset]);
+
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+ if (radix_tree_is_indirect_ptr(entry)) {
+ unsigned long siboff = get_slot_offset(parent, entry);
+ if (siboff < RADIX_TREE_MAP_SIZE) {
+ offset = siboff;
+ entry = rcu_dereference_raw(parent->slots[offset]);
+ }
+ }
+#endif
+
+ *nodep = (void *)entry;
+ return offset;
+}
+
static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
{
return root->gfp_mask & __GFP_BITS_MASK;